Heat Controller Water Source Heat Pump Occupied/Unoccupied Mode of Operation, Vent Mode Operation

WattMaster WHP Section 1

Occupied/Unoccupied Mode of Operation

Since the WHP contains its own built in Real Time Clock, it can operate from its own internal scheduling system. This schedule supports two Start & Stop events per day and up to 14 Holiday periods. The Holidays all use the same special Holiday Start/Stop times programmed by the user.

If the current operating mode is unoccupied, the WHP can accept a push-button override back to the occupied mode. Push-button overrides are not recognized if the current mode is already occupied. The push-button override duration is user programmed. If the user wants to extend the current override without reprogramming the Duration, they can re- initialize the existing programmed period by pressing the override button anytime during the current override. If the current override had been active for 1 hour and 45 minutes and the user presses the push-button again, the override will reset for another 2 hour period (if they programmed a 2 hour period), bringing the total override time to 3 hours and 45 minutes. If the user wants to cancel an override before it can time-out, simply hold the push-button for a period of time between 3 and 10 seconds.

The WHP calculates its current heating and cooling setpoints based on the current mode of operation. If the command is for unoccupied mode, the WHP adds the unoccupied setbacks to the occupied heating and cooling setpoints.

Vent Mode Operation

During occupied hours when there is no heating or cooling demand, the WHP reverts to a Vent Mode of operation. The fan is running and the heating and cooling outputs are held off.

See the section titled HVAC Mode of Operation for a graphical description of how the Vent Mode is calculated.

Off Mode of Operation

After the schedule goes unoccupied and both heating and cooling demands go away, the fan stops running, all relay outputs are turned off. No outputs are allowed to activate in the Off Mode until a heating or cooling demand occurs. During occupied hours this would be the Vent Mode.

Design Guide 1-7